Photographic elements having light-sensitive and water-insoluble vinylpyridine polymer layers



Sept. 7, 1948. SCHULZE 2,448,552

PHOTOGRAPHIC ELEMENTS HAVING LIGHT-SENSITIVE AND WATER-INSOLUBLE VINYLPYRIDINE POLYIER LAYERS Filed NOV. 27, 1946 FILM SUPPORT ANTl-ABRASION LAYER amxxxwws. GREEN ORRED SENSITIVE SILVER HALIDE EMULSION VINYL PYRIDINE POLYMER LAYER I INVENTOR.

FERDINAND SCHULZE BY I w BMW/m ATTORNEY Patented Sept. 7, 1948 PHOTOGRAPHIC ELEMENTS HAVING LIGHT-SENSITIVE AND WATER-IN- SOLUBLE VINYLPYRIDINE POLYMER LAYERS Ferdinand Schulze, Westfleld, N. J., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application November 27, 1946, Serial No. 712,723

8 Claims.

This invention relates to photography and, more particularly, to photographic elements which have removable light-sensitive layers. Still more particularly it relates to stripping photographic elements and to processes of using thde same in obtaining photographic image rec- Or 8.

An object of this invention is to provide photoraphic elements with removable or releasable layers and especially releasable light-sensitive layers. A further object is to provide photographic elements with novel stripping layers for temporarily adhering light-sensitive emulsion layers to a support. A still further object is to provide a multilayer photographic flhn with light-sensitive layers which can be readily separated from each other during processing. Another object is to provide such elements which have good adherence between the layers during treatment in alkaline developing baths and aqueous washing baths. Yet another object is to provide a bipack film with one element for recording two-color separation records from which one record can be readily removed after development has been completed. Still other objects will be apparent from the following description of the invention.

The novel photographic elements of this invention can be made by casting a light-sensitive silver halide emulsion layer onto a support, e. g., a film support, a vinylpyridine polymer layer is then cast onto the emulsion layer-and.another light-sensitive silver halide emulsion layer is coated onto the vinylpyridine polymer layer. An anti-abrasion layer may be coated onto the outer emulsion layer if desired. The respective emulsion layers are differentially sensitized so that they will record light from diiferent regions of the spectrum. They are preferably so disposed and sensitized that they are respectively sensitive to light from different primary color regions of the visible spectrum. A light screening dye or pigment can be placed in one of the layers or in the vinylpyridine polymer layer. The dye or pigment is preferably yellow in color so that the layer has blue light absorption characteristics.

A practical front film for a bipack has the inner silver halide emulsion layer predominantly sensitive to blue light only, whereas the outermost layer is'sensitive to blue light and, in addition, is strongly sensitive to green or red light. A light screening dye or pigment is placed either in the inner emulsion layer or in the vinylpyridine polymer layer. It should have good blue light absorption characteristics and allow 2 green and red light to expose the remaining emulsion layer.

The photographic elements described in the two preceding paragraphs are illustrated in the accompanying drawing wherein Fig. 1 constitutes a cross-sectional view of a suitable photographic element and Fig. 2 is a cross-sectional view of another suitable film element.

Referring now to Fig. 1 of the drawing, a support I has disposed thereon on one surface, in order, a silver halide emulsion layer 2, a vinylpyridine polymer layer 3, and a silver halide emulsion layer 4. The element Fig. 2 consists of a film support I which has, in order, on one surface thereof a blue-sensitive silver halide emulsion layer 5, a vinylpyridine polymer layer 6, a greenor red-sensitive silver halide emulsion layer I, and an antiabrasion layer 8.

The layers composed of vinylpyridine polymers are not dissolved by alkaline photographic developer solutions or by the water rinse or washing baths used after development. However, they are readily softened or solubilized by dilute acids including the acids present in and at the concentration usually employed in the ordinary acid photographic processing baths, such as acid stop baths, acid fixing baths, acid hardening fixing baths, acid bleach baths, reversal bleach baths, etc. They are removable in acid developing baths.

The vinylpyridine polymers can be made by polymerizing a monomeric vinylpyridine, e. g., alpha-, beta-, or gamma-vinylpyridine or a homologue thereof containing an alkyl radical of one to four carbon atoms in the pyridine ring, in a liquid medium by the aid of a polymerization catalyst. An organic solvent solution can be used if desired in which case inert organic solvents are used. However, emulsion polymerization is quite useful and bulk polymerization methods are effective. The polymerization is preferably carried out in an aqueous mineral acid solution or medium in the presence of a peroxy compound catalyst at temperatures from about 20 to 50 C. for a period of ten- The invention is not limited to the use of polyvinylpyridine, including the alkyl substituted polyvinylpyridines, because copolymers soluble in 1% aqueous acetic acid which contain up to 20% of another polymerizable vinyl or vinylidene compound having a single vinyl group (CI-I:=C are useful. Suitable compounds for copolymerization with a. monomeric vinylpyridine are styrene, acrylic esters and amides, alpha-alkyl-substituted acrylic esters and amides, acrylonitriles and methacrylonitriles.

In making the copolymers there may be used such materials as methyl or ethyl acrylates; methyl. ethyl, isobutyl, and methoxyethyl methacrylates; methacrylamide and N-methylacrylamide; acrylonitrile and methacrylonitrile; styrene; vinyl naphthalene, and the like or mixtures of two or more of these compounds.

In a preferred aspect of the invention. the polymers of unsubstituted alpha or 2-vinylpyridine or its interpolymers containing 1 to of a different interpolymerizable monomer are used. Such polymers are non-water-soluble synthetic resins soluble in alcohols, e. g.. methyl, ethyl, propyl, and butyl, and mixtures of such alcohols with ketones, e. g., acetone, methyl ethyl ketone, methyl propyl ketone, and methyl isobutyl ketone or in certain chlorinated hydrocarbons. e. g., trichlorethylene. They form clear, light-colored. nontacky films or coatings which are readily and completely soluble in dilute aqueous acids. e. g., acetic, hydrochloric, sulfamic, sulfuric, phosphoric. and oxalic acids.

A practical method of coating the vinylpyridine They may be advantageously dissolved in a watermiscible alcohol in an amount of 0.25 to 20% by weight of the alcohol. A filtering dye or pigment or colloidal silver may be dispersed in the coating solution. The solution is then applied to or coated onto the support or a layer on the support by any of the conventional coating methods. e. g.. coating from a hopper, by dipping, by transfer or beading rollers, by spraying, etc. The solvent is allowed to evaporate or a heated medium is passed over the coating to facilitate drying.

The vinylpyridine polymer layers should be of such a thickness that they may be readily stripped from the layer on which they are coated. This can be readily determined by a simple experiment with the surface onto which it is to be temporarily joined. Thicknesses of 0.0001 to 0.0005 inch, in general, are adequate. However, thinner layers, e. g., 0.05 to 2.0 microns usually adhere quite firmly to the usual water-permeable colloids.

The invention will be further illustrated by the following examples.

Example I A cellulose nitrate film base having a thin gelatin anchoring substratum is coated with a fiowable gelatino-silver iodobromide emulsion which has admixed therewith 50% of yellow colloidal silver to form a layer having a coating weight of about 52 mg. of AgBr per sq. dec. which is dried. Six grams of poly-2-vinylpyridine is dissolved in 200 cc. of methanol and the solution is coated onto the silver halide emulsion layer to a thickness of about 0.0001 inch. A gelatino-silver iodobromide emulsion containing 1,1'-diethyl-2,2'- cyanine iodide as an ortho sensitizing dye .is coated on the polyvinylpyridine layer to a weight of approximately 48 mg. per sq. dec. An anti- .4 abrasion layer is coated onto the emulsion layer from a solution containing 450 grams of gelatin per 14,400 grams of water. The resulting element is suitable as the front film for a bipack. A suitable rear film for a bipack is made by coating a cellulose nitrate film base bearing a thin gelatin substratum with a gelatino-silver iodobromide emulsion containin as a green blind sensitizing dye 1,1'-diethyl-2,4-carbocyanine iodide.

The two films were placed with the gelatin layers in contact and exposed to a color scene and processed as follows:

(1) Developed for ten minutes in a developer made by admixing the following components:

(2) Washed for two minutes in plain water.

-(3) The outer layer of the front film was then pressed into intimate contact with a second registered support comprising a transparent film base coated with a gelatin layer having a coating weight of about 75 mg. per sq. dec. which had been soaked in a solution containing one volume of 28% acetic acid and nine volumes of water to promote adhesion between the gelatin surfaces of the respective elements and to destroy the bond between the top and bottom emulsion layers. During the period of contact, the aqueous acetic acid in the plain gelatin layer permeated the contiguous developed green-sensitive layer and wetted the polyvinylpyridine layer loosening the bond between it and the green-sensitive layer which tion negatives suitable for registration color printing.

' Example II A photographic film as described in Example I was developed and put through a rinse bath for two minutes as described in that example. The developed film was then given a dilute acetic acid rinse and was then immediately squeegeed into intimate contact with a dry registered gelatin coated film blank which had been previously humidified to bring about necessary swelling to permit registration. The "dry" surface of the blank afi'orded instantaneous adhesion for the outer gelatin layer of the front film. The dilute acid adsorbed by the rinse penetrated the front film element and weakened the bond between the polyvinylpyridine surface and the outer emulsion layer so that it could be stripped in about one second from the appertainin layer which adhered to the gelatin layer of the blank,

Example III 2,4'-carbocyanine iodide is coated on the polyvinylpyridine layer to a weight of approximately 55 mg. p r sq. dec. The film is useful as a front film for a bipack.

EmmplelV A similar film base was coated with a thin gela-l tin substratum. A green-sensitive gelatino-silver iodobromide emulsion containing l,l'-diethyl- 2,2'-cyanine iodide was coated over the substraturn to give the rear film element 01' the bipack.

, The film elements were exposed and processed after the manner described in Example I yielded.

three-color separation negatives from which there could be printed three corresponding positives.

' A cellulose nitrate film base was provided with N-methyl-p-aminophenol su1tate-- grams 4.0 Sodium sulflte (anhydrous) .do 30.0 Hydroquinone do 3.0 Sodium carbonate (anhydrous) ..do 23.4 Potassium bromide do 20.0 Water to s" 1.0

whereby the upper layer is developed.

(3) The upper layer may be fixed at this stage, if desired, by fixing in a neutral fixing bath of the following composition: Sodium thiosuliate "grams" 20 Water liters 1 (4) Re-exposed with light through a gamma compensation filter to yield a proper gamma in lower layer.

(5) The upper layer is stripped from the lower layer by treatment in a 1% aqueous acetic acid bath.

(6) Developed in the same bath described in front film of a bipack which was exposed through the base.

Example v V g A double. weight paper is provided with a glossy baryta layer ,and is coated with a solution of pol 2-vinylpyridine as dcscribedin Example .I. A thin membrane or nitrocellulose is coatedonto the.

polymer layer from a solution comprising:

Grams Nitrocellulose (80-120 sec. IUD-12.1% N)--- 6.0 Glycerine 2.3 Urea. 2.3 Dibutylphthalate 1.2 Methyl alcohol 88.2

A thin gelatin layer is coated on the nitrocellulose membrane from a solution of the composition:

Grams Gelatin 1 Acetic acid (glacial) 3 Ethyl alcnhnl 26 Example VI A transparent cellulose acetate illm base provided with a thin gelatin anchoring substratum is coated with a positive type gelatino-silver halide emulsion of normal speed to a weight of 60+80 mg. of AgBr per sq. dec. A layer of polyvinylpyridine is coated from a solution like that in Example I onto the emulsion layer. A high speed panchromatic gelatino-silver iodobromide emulsion is coated onto the polyvinylpyridine layer to a weight of about 60 to 100 mg. of AgBr per sq. dec.

The film was then used in the following manher.

(1) Exposed in a camera or reproduction apparatus with an exposure which is correct for the upper layer.

(2) Developed for two minutes in a solution made by admixing the following components:

the preceding step 2.

(7) The base and developed layer is fixed in a solution of the following composition:

Sodium thiosuliate "grams" 200 Water to liters 1 (8) Washed and dried.

The upper layer may be stripped from the rest of the element at any time after re-exposure. It is preferable to remove it before the second development.

Example VII A cellulose acetate film base is provided with a filter layer composed of gelatin and a filter dye or pigment. A gelatino-silver halide emulsion layer is coated onto the filter layer. The other side of the base is then coated with a gelatino-silver halide emulsion layer. A layer of polyvinylpyridine is then coated on the latter layer from a solution as described in Example I.

The film base can, of course, be provided with silver halide layer because it is quite impervious to the alkaline developer solution which can be used for the development of the outer emulsion layer disposed on the other side of the base. The polyvinylpyridine layer can be removed by means of a 1% aqueous acetic acid bath and the adjacent exposed silver halide emulsion layer then developed in any suitable developer solution. The developer solutions may be free from or contain color formers, e. g., phenols, naphthols, pyrazolones, acetoacetic acid esters and amides, etc.

The film construction just described is of especial importance in the production of colored or dye images because it permits separate and independent optimum development of the exposed light-sensitive layers. Different color formers can be used in the respective developers so that a multicolor picture can be made. For example, if the light-sensitive layers are exposed to the blue-green and orange-red regions of the spectrum, the developer solutions therefor may respectively contain orange-red and blue-green color formers.

Suitable color formers and developing agents are described in United States Patents 1,102,028, 2,140,540, 2,166,181, 2,182,815, 2,184,303, and 2,294,909 and The British Journal of Photography, October 14, 1938, pages 647-648.

The vinylpyridine polymer layers are strongly adherent to all types of water-penneable colloid layers including those of natural and synthetic type, e. g., gelatin. agar agar, collodion, albumin, polyvinyl alcohol, and partially hydrolyzed polyvinyl esters, e. g., acetate and their ethers and acetals, hydrophilic polydioxolanes, polyamides (nylon), etc. They are also strongly adherent to hydrophobic materials useful as supports for photographic elements, e. g., polyamides, cellulose nitrate, polyvinyl'acetals, cellulose propionate, cellulose mixed esters, cellulose ethers, vinyl chloride and copolymers, styrene, acrylonitrile and copolymers, poly-esters, vinyl acetate and copolymers, vinyl fluoride and copolymers, polyvinyl alcohol, transparentized paper, etc.

An advantage of the invention is that it provides a number of novel and useful photographic elements and processes. It provides photographic elements with novel releasable or removable layers or strata. The vinylpyridine polymer layers have the advantage that they do not come oil! in developer solutions but yet can be readily removed by means of weak acid solutions. The layers are unaffected by water and do not readily permit the penetration of alkaline photographic developer solutions.

As many widely difierent embodiments of this invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not to be limited except as defined by the claims.

What is claimedis:

1. A photographic element comprising a support, a light-sensitive hydrophilic silver halide colloid layer on said support, and a water-insoluble vinylpyridine polymer layer which is soluble in 1% aqueous acetic acid and is in adhesive contact with the colloid layer.

2. A photographic element comprising a support, a light-sensitive hydrophilic gelatin silver halide emulsion layer on said support, and a water-insoluble vinylpyridine layer which is soluble in 1% aqueous acetic acid and is in adhesive contact with the emulsion layer.

3. A photographic element comprising a transparent support of light-sensitive hydrophilic colloid silver halide emulsion layer on said support, a water-insoluble vinylpyridine polymer layer which is soluble in 1% aqueous acetic acid on said emulsion layer, and a. light-sensitive hydrowater-insoluble poly-2-vinylpyridine layer which is soluble in 1% aqueous acetic acid on said emulsion layer, and a light-sensitive hydrophilic colloid silver halide emulsion layer on said polymer layer. I

5. A photographic element comprising a transparent support bearing in order on one side a light-sensitive hydrophilic colloid silver halide emulsion which is predominately sensitive to blue light, a water-insoluble vinylpyridine polymer layer which is soluble in 1% aqueous acetic acid and a light-sensitive hydrophilic colloid silver halide emulsion layer which is strongly sensitive to light in one of the higher primary color regions of the visible spectrum, at least one of the inner layers having good blue light absorption characteristics.

6. A photographic element comprising a transparent support bearing in order on one side a light-sensitive hydrophilic colloid silver halide emulsion which is predominately sensitive to blue light, a water-insoluble poly-Z-vinylpyridine layer which is soluble in 1% aqueous acetic acid and a light-sensitive hydrophilic colloid silver halide emulsion layer which is strongly sensitive to light in one of the higher primary color regions of the visible spectrum, at least one of the inner layers having good blue light absorption characteristics.

7. A photographic element comprising a transparent film base, a layer on one side of the support containing a light absorbing material bearing a hydrophilic colloid silver halide emulsion layer, a hydrophilic colloid silver halide emulsion layer on the other side of the support bearing a water-insoluble polyvinylpyridine layer which is soluble in 1% aqueous acetic acid, said material absorbing light of wave lengths to which the latter emulsion layer is sensitive.

8. A photographic element bearing a plurality of hydrophilic colloid silver halide emulsion layers at least two of which have an intercalated water-insoluble vinylpyridine polymer layer which is soluble in 1% aqueous acetic acid.

FERDINAND SCHULZE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

